A low-altitude new location for Equisetum palustre L. (Equisetales: Equisetaceae) in Jaén province (Spain)

Se presenta una nueva localidad de Equisetum palustre L. en el macizo de Cazorla-Segura, Jaén. Con una altitud de 460 msnm, este enclave difiere de las localidades previamente conocidas en esta zona, todas ellas situadas en ambientes montanos. La pre- sencia de E. palustre a baja altitud plantea dudas sobre la distribu- ción y abundancia real de esta especie en Andalucía, donde goza de protección legal

Selective Detection and Inhibition of Active Caspase‑3 in Cells with Optimized Peptides

Caspases are a family of cysteine-aspartyl proteases that are well recognized for their essential roles in apoptosis and inflammation. Recently, caspases have also been linked to the promotion of other biologically important phenomena, such as cellular differentiation and proliferation. Dysregulation of the multifaceted and indispensable activities of caspases has been globally linked to several diseases, including cancer and neurodegenerative disorders; however, the specific caspase members responsible for these diseases have yet to be assigned. Activity-based probes (ABPs) and peptide-based inhibitors are instrumental in the detection and control of protease activity and serve as alternative methods to genetic approaches. Such molecules aid in the interrogation of specific proteases within cellular and animal models as well as help elucidate aberrant proteolytic function correlated to disease phenotypes. No ABPs or inhibitors have been discovered that specifically target one of the eleven human caspases in a cellular context. Therefore, ascribing distinct contributions to an individual caspase activity within naturally occurring biological systems is not possible. Herein, we describe a peptide series optimized for the selective detection and inhibition of active caspase-3 in cells. These compounds exhibit low nanomolar potency against caspase-3 with >120-fold selectivity over caspase-7 which shares 77% active site identity. Our ability to individually target wild-type active caspase-3 for detection and cell permeable inhibition is a valuable proof-of-concept methodology that can be readily employed to probe the significance of caspase-3 in apoptosis, neurological disorders, cardiovascular diseases, and sepsis

Selective Detection of Caspase‑3 versus Caspase‑7 Using Activity-Based Probes with Key Unnatural Amino Acids

Caspases are required for essential biological functions, most notably apoptosis and pyroptosis, but also cytokine production, cell proliferation, and differentiation. One of the most well studied members of this cysteine protease family includes executioner caspase-3, which plays a central role in cell apoptosis and differentiation. Unfortunately, there exists a dearth of chemical tools to selectively monitor caspase-3 activity under complex cellular and <i>in vivo</i> conditions due to its close homology with executioner caspase-7. Commercially available activity-based probes and substrates rely on the canonical DEVD tetrapeptide sequence, which both caspases-3 and -7 recognize with similar affinity, and thus the individual contributions of caspase-3 and/or -7 toward important cellular processes are irresolvable. Here, we analyzed a variety of permutations of the DEVD peptide sequence in order to discover peptides with biased activity and recognition of caspase-3 versus caspases-6, -7, -8, and -9. Through this study, we identify fluorescent and biotinylated probes capable of selective detection of caspase-3 using key unnatural amino acids. Likewise, we determined the X-ray crystal structures of caspases-3, -7, and -8 in complex with our lead peptide inhibitor to elucidate the binding mechanism and active site interactions that promote the selective recognition of caspase-3 over other highly homologous caspase family members

Por D. Iuana Zapata Osorio condesa de Casarrubios, viuda de D. Gonçalo Chacon, conde que fue dela [sic] dicha villa. Con el señor Lic. D. Iuan Gonçalez, Cauallero dela Orden de Santiago, del Consejo y Camara de Indias de su Magestad, como marido de la

A 109/116(04

Identification and Co-complex Structure of a New <i>S. pyogenes</i> SpeB Small Molecule Inhibitor

The secreted <i>Streptococcus pyogenes</i> cysteine protease SpeB is implicated in host immune system evasion and bacterial virulence. We present a small molecule inhibitor of SpeB <b>2477</b> identified from a high-throughput screen based on the hydrolysis of a fluorogenic peptide substrate Ac-AIK-AMC. <b>2477</b> inhibits other SpeB-related proteases but not human caspase-3, suggesting that the molecule targets proteases with the papain-like structural fold. A 1.59 Å X-ray crystal structure of <b>2477</b> bound to the SpeB active site reveals the mechanism of inhibition and the essential constituents of <b>2477</b> necessary for binding. An assessment against a panel of <b>2477</b> derivatives confirms our structural findings and shows that a carbamate and nitrile on <b>2477</b> are required for SpeB inhibition, as these moieties provide an extensive network of electrostatic and hydrogen-bonding interactions with SpeB active site residues. Surprisingly, despite <b>2477</b> having a reduced inhibitory potential against papain, the majority of <b>2477</b>-related compounds inhibit papain to a much greater and broader extent than SpeB. These findings indicate that SpeB is more stringently selective than papain for this panel of small molecule inhibitors. On the basis of our structural and biochemical characterization, we propose modifications to <b>2477</b> for subsequent rounds of inhibitor design that will impart specificity to SpeB over other papain-like proteases, including alterations of the compound to exploit the differences in CA protease active site pocket sizes and electrostatics

Discovery of a Highly Selective Caspase‑3 Substrate for Imaging Live Cells

Caspases are a family of cysteine proteases that are well-known for their roles in apoptosis and inflammation. Recent studies provide evidence that caspases are also integral to many additional cellular processes, such as differentiation and proliferation. Likewise, aberrant caspase activity has been implicated in the progression of several diseases, including neurodegenerative disorders, cancer, cardiovascular disease, and sepsis. These observations establish the importance of caspases to a diverse array of physiological functions and future endeavors will undoubtedly continue to elucidate additional processes that require caspase activity. Unfortunately, the existence of 11 functional human caspases, with overlapping substrate specificities, confounds the ability to confidently assign one or more isoforms to biological phenomena. Herein, we characterize a first-in-class FRET substrate that is selectively recognized by active caspase-3 over other initiator and executioner caspases. We further apply this substrate to specifically image caspase-3 activity in live cells undergoing apoptosis